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Fructose 2,6-bisphosphate

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Fructose 2,6-bisphosphate
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
MeSH fructose+2,6-bisphosphate
PubChem CID
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C7H16O12P2/c8-2-7(3-18-21(14,15)16)6(10)5(9)4(19-7)1-17-20(11,12)13/h4-6,8-10H,1-3H2,(H2,11,12,13)(H2,14,15,16)/t4-,5-,6+,7+/m1/s1Key: NSKBXJZGSYZROA-JWXFUTCRSA-N
  • InChI=1/C7H16O12P2/c8-2-7(3-18-21(14,15)16)6(10)5(9)4(19-7)1-17-20(11,12)13/h4-6,8-10H,1-3H2,(H2,11,12,13)(H2,14,15,16)/t4-,5-,6+,7+/m1/s1Key: NSKBXJZGSYZROA-JWXFUTCRBS
SMILES
  • O=P(O)(O)OC1O(CO)(COP(O)(O)=O)(O)1O
Properties
Chemical formula C6H14O12P2
Molar mass 340.116 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

Fructose 2,6-bisphosphate abbreviated Fru-2,6-P2, is a metabolite that allosterically affects the activity of the enzymes phosphofructokinase 1 (PFK-1) and fructose 1,6-bisphosphatase (FBPase-1) to regulate glycolysis and gluconeogenesis. Fru-2,6-P2 is synthesized and broken down by the bifunctional enzyme phosphofructokinase 2/fructose-2,6-bisphosphatase (PFK-2/FBPase-2).

The synthesis of Fru-2,6-P2 is performed through the phosphorylation of fructose 6-phosphate using ATP by the PFK-2 portion of the enzyme. The breakdown of Fru-2,6-P2 is catalyzed by dephosphorylation by FBPase-2 to produce Fructose 6-phosphate and Pi.

Reaction scheme of breakdown of fructose 2,6-bisphosphate to fructose 6-phosphate.

Effects on glucose metabolism

Fru-2,6-P2 strongly activates glucose breakdown in glycolysis through allosteric modulation of phosphofructokinase 1. Elevated expression of Fru-2,6-P2 levels in the liver allosterically activates phosphofructokinase 1 by increasing the enzyme’s affinity for fructose 6-phosphate, while decreasing its affinity for inhibitory ATP and citrate. At physiological concentration, PFK-1 is almost completely inactive, but interaction with Fru-2,6-P2 activates the enzyme to stimulate glycolysis and enhance breakdown of glucose.

Production regulation

The concentration of Fru-2,6-P2 in cells is controlled through regulation of the synthesis and breakdown by PFK-2/FBPase-2. The primary regulators of this are the hormones insulin and glucagon, which affect the enzyme through phosphorlyation/dephosphorylation reactions. Release of the hormone glucagon triggers production of cyclic adenosine monophosphate (cAMP), which activates a cAMP-dependent protein kinase. This kinase phosphorylates the PFK-2/FBPase-2 enzyme at an NH2-terminal Ser residue with ATP to activate the FBPase-2 activity and inhibit the PFK-2 activity of the enzyme, thus reducing levels of Fru-2,6-P2 in the cell. With decreasing amounts of Fru-2,6-P2, glycolysis becomes inhibited while gluconeogenesis is activated. Insulin triggers the opposite response. As a phosphoprotein phosphatase, insulin dephosphorylates the enzyme, thus activating the PFK-2 and inhibiting the FBPase-2 activities. With additional Fru-2,6-P2 present, activation of PFK-1 occurs to stimulate glycolysis while inhibiting gluconeogenesis.

Regulation of sucrose production

Fru-2,6-P2 plays an important role in the regulation of triose phosphates, the end products of the Calvin Cycle. In the Calvin Cycle, 5/6th of triose phosphates are recycled to make ribulose 1,5-bisphosphate. The remaining 1/6 of triose phosphate can be converted into sucrose or stored as starch. Fru-2,6-P2 inhibits production of fructose 6-phosphate, a necessary element for sucrose synthesis. When the rate of photosynthesis in the light reactions is high, triose phosphates are constantly produced and the production of Fru-2,6-P2 is inhibited, thus producing sucrose. Fru-2,6-P2 production is activated when plants are in the dark and photosynthesis and triose phosphates are not produced.

See also

References

  1. ^ Lange AJ. "fructose-2,6-bisphosphate". University of Minnesota. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  2. Wu C, Khan SA, Peng LJ, Lange AJ (2006). "Roles for fructose-2,6-bisphosphate in the control of fuel metabolism: beyond its allosteric effects on glycolytic and gluconeogenic enzymes". Adv. Enzyme Regul. 46 (1): 72–88. doi:10.1016/j.advenzreg.2006.01.010. PMID 16860376.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Kurland IJ, Pilkis SJ (1995). "Covalent control of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: insights into autoregulation of a bifunctional enzyme". Protein Sci. 4 (6): 1023–37. doi:10.1002/pro.5560040601. PMC 2143155. PMID 7549867. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. KEGG REACTION: R02730
  5. Smith WE, Langer S, Wu C, Baltrusch S, Okar DA (2007). "Molecular coordination of hepatic glucose metabolism by the 6-phosphofructo-2-kinase/fructose-2,6- bisphosphatase:glucokinase complex". Mol. Endocrinol. 21 (6): 1478–87. doi:10.1210/me.2006-0356. PMID 17374851. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  6. Nielsen TH, Rung JH, Villadsen D (2004). "Fructose-2,6-bisphosphate: a traffic signal in plant metabolism". Trends Plant Sci. 9 (11): 556–63. doi:10.1016/j.tplants.2004.09.004. PMID 15501181. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
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